Hi all
I've currently got a vaulted ceiling in a lounge in a very old stone cottage. There are no eaves as such or ventilation, it has a slate roof with felt beneath.
Between the rafters is fiberglass insulation only.
Beneath the rafters is a plastic sheeting that i'm assuming was added as a vapour barrier.
There is no air gap to be seen.
Beneath the plastic sheeting is wooden tongue and groove that is attached to the underside of the rafter (tacked through the plastic sheeting)
As it a large room, the heat loss must be massive and so I am wanting to add insulation to the underside of the existing ceiling. My thoughts on options were:
A - remove the existing tongue and groove boarding. Add a multifoil insulation (that will also act as a vapour barrier), then batten to create a circa 25mm air gap, then plasterboard with either 37.5mm board (25mm, insulation/ 12.5mm plasterboard) or 62mm insulated plasterboard (50mm insulation/ 12.5mm plasterboard).
or
B - use insulated plasterboard (62mm?) directly onto either the existing tongue and groove (saves the mess of taking it down) and have no air gap. Do I need an air gap if there isn't one currently and it's not causing an issue?
or
C - remove the existing tongue and groove boarding, replace the vapour barrier, install PIR boards, then plaster over this. Questions: would an air gap be beneficial anywhere here?
I can't see any sign of condensation currently and the existing ceiling/ vapour barrier has been like this for 30 plus years with no dampness.
thanks in advance.
Picture to give you an idea - i'd like to keep the main beams exposed so have circa 100mm to play with.
I've currently got a vaulted ceiling in a lounge in a very old stone cottage. There are no eaves as such or ventilation, it has a slate roof with felt beneath.
Between the rafters is fiberglass insulation only.
Beneath the rafters is a plastic sheeting that i'm assuming was added as a vapour barrier.
There is no air gap to be seen.
Beneath the plastic sheeting is wooden tongue and groove that is attached to the underside of the rafter (tacked through the plastic sheeting)
As it a large room, the heat loss must be massive and so I am wanting to add insulation to the underside of the existing ceiling. My thoughts on options were:
A - remove the existing tongue and groove boarding. Add a multifoil insulation (that will also act as a vapour barrier), then batten to create a circa 25mm air gap, then plasterboard with either 37.5mm board (25mm, insulation/ 12.5mm plasterboard) or 62mm insulated plasterboard (50mm insulation/ 12.5mm plasterboard).
or
B - use insulated plasterboard (62mm?) directly onto either the existing tongue and groove (saves the mess of taking it down) and have no air gap. Do I need an air gap if there isn't one currently and it's not causing an issue?
or
C - remove the existing tongue and groove boarding, replace the vapour barrier, install PIR boards, then plaster over this. Questions: would an air gap be beneficial anywhere here?
I can't see any sign of condensation currently and the existing ceiling/ vapour barrier has been like this for 30 plus years with no dampness.
thanks in advance.
Picture to give you an idea - i'd like to keep the main beams exposed so have circa 100mm to play with.
